But the meatball – made from beef – is soon to be joined by at least two other varieties produced with a much lighter carbon footprint.

"The world loves IKEA meatballs," says Mona Liss, a corporate spokeswoman. "They're not going away. But sustainability initiatives are a cornerstone of IKEA."

So, the assemble-it-yourself furniture chain says that in 2015, it plans to add chicken and vegetarian meatballs in the U.S. market – both still under development. Like most major retailers, IKEA is eager to improve its status with Millennials who typically have greater concerns about sustainability.

Sustainability has been on IKEA's radar for years. Back in 2007, it was among the first U.S. retailers to phase out plastic shopping bags at stores. In 2010, it announced plans to phase out incandescent bulbs and will go 100% LED lighting by 2016. It also is building a U.S. windfarm.

But, truth-be-told, the chain may be almost as well-known for its Swedish meatballs as for its do-it-yourself furniture. And it sells ton of them. In 2013, it sold 97.4 million in the U.S., or 268,412 every day, Liss says. The current meatballs are made with beef and pork.

Its meatballs also made news in early 2013 when IKEA withdrew them from markets across Europe when traces of horse meat were found in them during a much wider European food scandal that involved horse meat found in products sold by many large food companies.

With that scandal in the rear-view mirror, meatballs remain a huge draw at IKEA. Just how huge? Think of it this way: IKEA's U.S. restaurants serve about 48.4 million guests annually. The top selling menu item? You guessed it: meatballs.